CHEMICAL CONTROL OF BACTERIAL BLIGHT OF WALNUT, THREE YEARS OF RESULTS

Walnut blight is the major disease in walnut orchards of France. The causal bacterium, Xanthomonas campestris pv juglandis, can infect leaves, catkins, buds, nuts and can induce up to 50 % losses of crops. During the last three years, different copper compounds (sulphate, hydroxide, oxide) were tested alone or supplemented with EBDC material, boron or iron. Five sprays were applied on the Cultivar Franquette during female flowering and the beginning of fruit increasing. From June to the harvest (end of September), the disease intensity was measured by counting the percent of nuts dropped. Apical necrosis were distinguished from the lateral ones. A correlation was noted between disease intensity and during moistening in may. Bordeaux mixture alone shown a limited efficiency. Copper hydroxide, even with restricted dose, was more effective. It was the same with copper oxide. Copper mixed with iron or boron wasn’t more effective. In fact, copper compounds plus EBDC material were the most effective. All these treatments had a similar effect on lateral and apical necrosis.

IV International Walnut Symposium

T. Ginibre, J.P. Prunet

blight, Xanthomonas juglandis, walnut, control, copper

https://doi.org/10.17660/ActaHortic.2001.544.55